GAZA/CAIRO - Talks in Cairo on ending the Gaza war showed no signs of a breakthrough on Monday, with Israel and the Palestinians entrenched in their demands hours before the expiry of a five-day ceasefire.

The truce is due to run out at 2100 GMT. A Palestinian source quoted by Egypt's state news agency MENA said Egyptian mediators were making "a big effort to reach an agreement in the coming hours".

Both sides said gaps remained in reaching a long-term deal that would keep the peace between Israel and fighting groups in the Gaza Strip, dominated by Hamas, and allow reconstruction aid to flow in after five weeks of fighting. Israeli Justice Minister Tzipi Livni addressed the prospect of renewed hostilities, while signalling that Israel would continue to hold its fire as long as Palestinians did the same. "If they shoot at us, we will respond," Livni, a member of Prime Minister Benjamin Netanyahu's security cabinet, told Israel Radio.

The Palestinian Health Ministry put the Gaza death toll at 2,016 and said most were civilians in the small, densely populated coastal territory. Sixty-four Israeli soldiers and three civilians in Israel have been killed.

Late on Sunday, a Palestinian official said Israel's position in the talks, as presented to them by Egyptian mediators, was a "retreat from what had already been achieved and discussions had returned to square one".

The official, who was not named, told MENA that Israel had toughened its stance and had presented "impossible" demands, particularly on security issues. He said the Palestinians would review the situation and offer their response on Monday.

"We are determined to achieve the demands of our people and foremost is ending the aggression and launching the rebuilding process and lifting the Israeli-imposed blockade of the Gaza Strip," MENA quoted the official as saying. Netanyahu said on Sunday that any deal on the territory's future had to meet Israel's security needs. He warned Hamas it faced "harsh strikes" if it resumed its attacks. Hamas also seeks the construction of a Gaza sea port and the reopening of an airport destroyed in previous conflicts, as part of any enduring halt to violence. Livni said such issues should be dealt with at a later stage. Israel, which launched its offensive on July 8 after a surge in Hamas rocket fire across the border, has shown scant interest in making sweeping concessions, and has called for the disarming of the fighting groups in the enclave of 1.8 million people. Hamas has said that laying down its weapons is not an option.

In Jerusalem, the Shin Bet internal security agency said it had arrested 93 Hamas activists in the occupied West Bank over the past three months who had planned to carry out "serious attacks" in Israel, aiming to destablise the region and eventually topple the Western-backed Palestinian Authority.

The Shin Bet allegations of a planned coup, in a statement that said Israeli authorities had confiscated 30 guns, seven rocket launchers and $170,000 from the group, were met with scepticism by Israeli media commentators.

"Would they have been able to do this? I don't know," Roni Daniel, the well-connected military affairs correspondent for Israel's Channel Two television, said on-air.

Meanwhile, the Israeli army said Monday it had destroyed the homes of two of three Palestinians suspected of involvement in the kidnapping and murder of three Israeli teenagers in June.

Naftali Frenkel, Gilad Shaer and Eyal Yifrach disappeared from a hitchhiking stop in the southern West Bank on June 12 and their bodies were found June 30, with Israel blaming Hamas fighters. The incident triggered a series of events which led to the currently bloody standoff in Gaza where Israel and Hamas have been locked in a violent confrontation for more than a month.

Israel has named three Palestinians from the southern city of Hebron as being behind the abduction - Hossam Qawasmeh, who was arrested in July, and Marwan Qawasmeh and Amer Abu Eisha - both of whom are still at large.

"Overnight, as part of the ongoing mission to combat terror in the region, security personnel demolished the residences of Hossam Qawasmeh, and Amer Abu Eisha, and sealed off the residence of Marwan Qawasmeh in Hebron," an army statement said.

The homes of Marwan Qawasmeh and Abu Eisha had been partially destroyed by the army on July 1, a day after the teens' bodies were found, Palestinian witnesses told AFP at the time.

At the scene, an AFP correspondent confirmed the demolition of two of the houses and said a third had been sealed off with concrete.